The present invention relates to a defect inspection method and a defect inspection device used to inspect the quality of devices such as a semiconductor product, a magnetic head, a magnetic disk, a solar battery, an optical module, a light emitting diode, or a liquid crystal display panel, each of which is formed by repeating film formation, resist coating, exposure, development, etching, and the like on a substrate. Such a defect inspection method and a defect inspection device, for example, are used to inspect the dimension of a formed pattern, and the size and shape of a defect that has occurred, and the like. The present invention particularly relates to a defect inspection method and a defect inspection device which use a digital camera for an electron microscope or an optical microscope.
In recent years, electron microscopes are widely used to inspect the qualities of semiconductor products, magnetic heads, magnetic disks, solar batteries, optical modules, light emitting diodes, liquid crystal display panels, and the like, for example, to inspect a dimension of a formed pattern and the size and shape of a defect occurred.
In order to observe a pattern or a defect on a substrate using an electron microscope, a stage that holds thereon a substrate to be observed is moved so that specified XY coordinates are located near the center of an image. Next, a Z coordinate of the stage is moved so that the pattern or the defect is focused, and the image is acquired.
JP-A-2009-194272 (Patent Document 1) describes a method for registering an offset, called a focus map, of a Z coordinate in order to shorten a scanning range of the Z coordinate (in the direction of a normal to a stage surface on which a substrate is placed) and performing focusing the offset as a standard. In this method, a Z coordinate that causes a focal point to be adjusted to each of various positions on a certain substrate is measured, and a curved surface is approximated for measured XYZ coordinate groups, and the approximated curved surface is registered in an electron microscope as a focus map. Next, when another substrate is observed using the electron microscope, a Z coordinate that causes the focal point to be adjusted to certain XY coordinates is assumed to be close to the Z coordinate corresponding to the XY coordinates of the registered focus map, the Z coordinate is moved around the assumed Z coordinate, and focusing is performed.